基于机器视觉的双凸透镜缺陷检测研究

Research on biconvex lens defect detection based on machine vision

双凸透镜缺陷检测作为评估透镜质量性能的重要环节,根据双凸透镜成像原理和视觉检测的方法,提出了一种基于机器视觉的双凸透镜缺陷检测方法。由点激光器将光束打在直径为8 mm双凸透镜表面,产生亮光斑或亮光带的原理,搭建了基于成像缺陷检测方法的图像采集系统来获取麻点、划痕和破边等缺陷。采用椭圆拟合算法将透镜投影区域从背景中分割,根据求出的几何参数建立同心椭圆模型实现对投影区域的分区处理,对内椭圆进行基于改进粒子群优化的最大类间方差(Otsu)算法进行缺陷提取,采用基于形态学的开闭运算和区域标记算法来完成对缺陷大小的计算;对外椭圆进行条纹中心线提取,通过检测断点,找出缺陷的位置信息。实验结果表明,该方法能够准确检测出透镜中所有缺陷,检测精度为0.065 mm。

Biconvex lens defect detection is an important part of evaluating lens quality and performance.According to the imaging principle of biconvex lens and the method of visual detection,a biconvex lens defect detection method based on machine vision is proposed.According to the principle that the spot laser hits the beam on the surface of a biconvex lens with a diameter of 8 mm to produce a bright spot or bright band,an image acquisition system based on the imaging defect detection method is built to obtain pitting,scratches,broken edges and other defects.The ellipse fitting algorithm is used to segment the lens projection area from the background,and the concentric ellipse model is established according to the calculated geometric parameters to realize the partition processing of the projection area.The defect of the inner ellipse is extracted by Otsu algorithm based on improved particle swarm optimization,and the defect size is calculated by opening and closing operation based on morphology and region marking algorithm.The fringe centerline of the outer ellipse is extracted,and the location information of the defect is found by detecting the breakpoint.The experimental results show that this method can accurately detect all defects in the lens,and the detection accuracy is 0.065 mm.